Production method for partially separated fiber bundle, partially separated fiber bundle, fiber-reinforced resin molding material using partially separated fiber bundle, and production method for fiber-reinforced resin molding material using partially separated fiber bundle

ABSTRACT

A method of producing a partially separated fiber bundle includes a partial separation processing step for alternately forming separation-processed sections, each divided into a plurality of bundles, and not-separation-processed sections along the lengthwise direction of a fiber bundle, wherein a separation means provided with a plurality of projected parts is penetrated into the fiber bundle to create separation-processed parts, the separation means is removed from the fiber bundle, and the separation means is penetrated into the fiber bundle again, characterized in that a sizing agent is applied at an arbitrary timing during the production process of the partially separated fiber bundle. A partially separated fiber bundle is obtained by the production method, a fiber-reinforced resin molding material uses the partially separated fiber bundle, and a production method makes the fiber-reinforced resin molding material.

TECHNICAL FIELD

This disclosure relates to a method of producing a partially separatedfiber bundle and a partially separated fiber bundle obtained by themethod and, more specifically, to a production method for a partiallyseparated fiber bundle wherein, when performing a specified partialseparation processing to a fiber bundle of an inexpensive large towhaving a large number of single fibers not expected with separation toform a partially separated fiber bundle with an optimal form to producea molding material used for molding a composite material, a sizing agentis applied at an appropriate timing (when a sizing agent is applied toan original fiber bundle, an additional sizing agent is applied), and apartially separated fiber bundle obtained by the method, afiber-reinforced resin molding material impregnated with resin aftermatting the partially separated fiber bundle, and a production methodthereof comprising a series of steps until the material is manufactured.

BACKGROUND

A technology to produce a molded article having a desired shape is knownin which a molding material comprising a bundle-like aggregate ofdiscontinuous reinforcing fibers (for example, carbon fibers)(hereinafter, also referred to as a fiber bundle) and a matrix resin isused and it is molded by heating and pressurizing. In such a moldingmaterial, a molding material comprising a fiber bundle having a largenumber of single fibers is excellent in flowability at the time ofmolding, but tends to be inferior in mechanical properties of a moldedarticle. On the other hand, a fiber bundle adjusted to an arbitrarynumber of single fibers is used as a fiber bundle in the moldingmaterial, aiming to satisfy both the flowability at the time of moldingand the mechanical properties of the molded article.

As a method of adjusting the number of single fibers of the fiberbundle, for example, JP-A-2002-255448 and JP-A-2004-100132 disclosemethods of performing a separation processing using a plurality of fiberbundle winding bodies prepared by winding a plurality of fiber bundlesin advance. In those methods, however, because the number of singlefibers of each fiber bundle treated in advance is restricted, theadjustment range is limited and, therefore, it is difficult to adjust toa desired number of single fibers.

Further, for example, JP-A-2013-49208, JP-A-2014-30913 and JapanesePatent No. 5512908 disclose methods of longitudinally slitting a fiberbundle to a desired number of single fibers by using disk-shaped rotaryblades. In those methods, although it is possible to adjust the numberof single fibers by changing the pitch of the rotary blades, since thefiber bundle longitudinally slit over the entire length in thelengthwise direction has no convergence property, the yarn after thelongitudinal slit tends to become difficult in handling such as windingit on a bobbin or unwinding the fiber bundle from the bobbin. Inaddition, when conveying the fiber bundle after the longitudinalslitting, the split end-like fiber bundle generated by the longitudinalslit may be wrapped around a guide roll, a feed roll or the like, whichmay not be easy to convey.

Further, WO 2012/105080 discloses a method of cutting a fiber bundle toa predetermined length at the same time as a longitudinal slit by aseparation cutter having a lateral blade perpendicular to the fiberdirection in addition to a longitudinal blade having a longitudinal slitfunction in a direction parallel to the fiber direction. According tothat method, it becomes unnecessary to once wind the fiber bundle afterthe longitudinal slit to the bobbin and transport it, and the handlingproperty is improved. However, since the separation cutter has thelongitudinal blade and the lateral blade, when one of the blades reachesthe cutting life first, an obstacle arises that the entire blade has tobe exchanged.

Further, for example, JP-A-2011-241494 and US Patent Publication No.2012/0213997 A1 describe a method in which a roll having a plurality ofprojections is provided on the outer circumferential surface of theroll, and the projections of the roll is pushed into a fiber bundle topartially separate the fiber bundle. In that method, however, becausethe circumferential speed of the roll and the conveying speed of thefiber bundle are basically the same speed synchronized with each other,it is impossible to control the lengths and the like of theseparated-processed section and the not-separated-processed section, andit is difficult to obtain a partially separated fiber bundle with anoptimal form.

Furthermore, EP-A-2687356 A1 describes a special method of formingintermittently extending flow paths to facilitate resin impregnation ina fiber bundle by a monofilament extending in a direction orthogonal tothe fiber bundle. However, this manner relates to a technology offorming a flow path to facilitate resin impregnation in a fiber bundle,and therefore, it is basically a technology different from separation ofa fiber bundle such as large tow.

As described above, to satisfy both flowability during molding andmechanical properties of a molded article, a fiber bundle adjusted to anarbitrary optimal number of single fibers is required. Further, even ifa fiber bundle of a large tow can be separated into thin fiber bundleshaving an optimal number of single fibers, there is a possibility thatthe separated fiber bundles may be reaggregated from some reason and, ifreaggregated, it becomes difficult to maintain the form of the fiberbundles adjusted at the optimal number of single fibers. If the form ofthe fiber bundles adjusted at the optimal number of single fibers cannotbe maintained, when making a fiber-reinforced resin molding materialobtained by cutting/spraying the separated fiber bundles andimpregnating a resin, it becomes difficult to make it into a moldingmaterial with an optimal form, and it becomes difficult to exhibit theflowability during molding and the mechanical properties of a moldedarticle at a good balance.

Further, as described above, if the fiber bundle is not separatedadequately, when making a fiber-reinforced resin molding materialobtained by cutting/spraying the separated fiber bundle and impregnatinga resin thereinto, it may become difficult to stably unwind the fiberbundle from a bobbin or the like for cutting and troubles such aswinding around a conveyance roller or a cutting blade may occur.

Accordingly, it could be helpful to provide a method of producing apartially separated fiber bundle capable of performing a specifiedpartial separation processing capable of forming a fiber bundle with anoptimal number of single fibers of manufacturing a molding material usedfor molding a composite material, and capable of preventing aninadequate reaggregation and the like from occurring in the producedpartially separated fiber bundle and, further, capable of obtaining anexcellent process stability and improving a productivity even whensubjecting the partially separated fiber bundle to a processing such ascutting.

Further, it could be helpful to provide a fiber-reinforced resin moldingmaterial in which the partially separated fiber bundle obtained theabove-described production method is matted and impregnated with aresin, and a method of producing a fiber-reinforced resin moldingmaterial having a series of steps up to manufacture it.

SUMMARY

We thus provide:

(1) A method of producing a partially separated fiber bundle comprisinga partial separation processing step for alternately formingseparation-processed sections, each divided into a plurality of bundles,and not-separation-processed sections, wherein, while a fiber bundlecomprising a plurality of single fibers is traveled along the lengthwisedirection of the fiber bundle, a separation means provided with aplurality of projected parts is penetrated into the fiber bundle tocreate a separation-processed part, and entangled parts, where thesingle fibers are interlaced, are formed at contact parts with theprojected parts in at least one separation-processed part, thereafterthe separation means is removed from the fiber bundle, and after passingthrough an entanglement accumulation part including the entangled parts,the separation means is penetrated again into the fiber bundle,characterized in that a sizing agent is applied at an arbitrary timingduring the production process of the partially separated fiber bundle.When a sizing agent is applied to an original fiber bundle, anadditional sizing agent is applied. It is same also in the followingmethods.(2) A method of producing a partially separated fiber bundle comprisinga partial separation processing step for alternately formingseparation-processed sections, each divided into a plurality of bundles,and not-separation-processed sections, wherein a separation meansprovided with a plurality of projected parts is penetrated into a fiberbundle comprising a plurality of single fibers, while the separationmeans is traveled along the lengthwise direction of the fiber bundle, aseparation-processed part is created, and entangled parts, where thesingle fibers are interlaced, are formed at contact parts with theprojected parts in at least one separation-processed part, thereafterthe separation means is removed from the fiber bundle, and after theseparation means is traveled up to a position passing through anentanglement accumulation part including the entangled parts, theseparation means is penetrated again into the fiber bundle,characterized in that a sizing agent is applied at an arbitrary timingduring the production process of the partially separated fiber bundle.(3) The method of producing a partially separated fiber bundle accordingto (1) or (2), wherein after widening the width of the fiber bundle, thefiber bundle is supplied to the partial separation processing step.(4) The method of producing a partially separated fiber bundle accordingto (3), wherein after applying a sizing agent to the fiber bundlewidened in width, the fiber bundle is supplied to the partial separationprocessing step.(5) The method of producing a partially separated fiber bundle accordingto any one of (1) to (4), wherein the application processing of thesizing agent has at least the following steps [1] and [2], and each stepis individually performed at an arbitrary timing.

[1] sizing agent applying step

[2] drying step

(6) The method of producing a partially separated fiber bundle accordingto (5), wherein the width of the fiber bundle before drying is widenedthrough the step [1], the widened fiber bundle is subjected to the step[2], the fiber bundle having undergone the sizing agent applicationprocessing and the widening processing is supplied to the partialseparation processing step.(7) A partially separated fiber bundle obtained by the production methodaccording to any one of (1) to (6).(8) A fiber-reinforced resin molding material comprising a reinforcingfiber mat obtained by cutting and spraying the partially separated fiberbundle according to (7) and a matrix resin.(9) The fiber-reinforced resin molding material according to (8),wherein the matrix resin is a thermosetting resin.(10) The fiber-reinforced resin molding material according to (8) or (9)9, wherein the fiber-reinforced resin molding material is a sheetmolding compound.(11) A method of producing a fiber-reinforced resin molding materialaccording to any one of (8) to (10), comprising at least the followingsteps [A] to [C]:

-   -   [A] a partial separation step of obtaining a partially separated        fiber bundle by alternately forming separation-processed parts,        each divided into a plurality of bundles, and        not-separation-processed parts along a lengthwise direction of a        fiber bundle comprising a plurality of single fibers, and        applying a sizing agent at an arbitrary timing during the        production process of the partially separated fiber bundle;    -   [B] a matting step of cutting the partially separated fiber        bundle and spraying the cut bundles to obtain a reinforcing        fiber mat; and    -   [C] a resin impregnation step of impregnating a matrix resin        into the reinforcing fiber mat.        (12) The method of producing a fiber-reinforced resin molding        material according to (11), wherein at least the steps [A] to        [C] are carried out continuously in a single process.        (13) The method of producing a fiber-reinforced resin molding        material according to (11) or (12), wherein in the step [B], the        partially separated fiber bundle is cut at an angle θ (0<θ<90°)        with respect to the lengthwise direction thereof.

In the method of producing a partially separated fiber bundle, in thespecified production of a partially separated fiber bundle performedwith separation while the fiber bundle is traveled or while theseparation means is traveled, since a sizing agent is applied at anarbitrary timing during the production process of the partiallyseparated fiber bundle, a reaggregation can be prevented from occurringin the partially separated fiber bundle performed with an optimalpartial separation processing, and it becomes possible to maintain theoptimal partial separation processing state. As a result, when making afiber-reinforced resin molding material by cutting/spraying thepartially separated fiber bundle maintained at the optimal partialseparation processing state and impregnating a resin thereinto, itbecomes possible to mix thin fiber bundles and thick fiber bundleswithin a range of an optimal ratio, thereby exhibiting the flowabilityduring molding and the mechanical properties of a molded article at agood balance.

Further, when cutting the above-described partially separated fiberbundle by, for example, a cutter, an effect of improving unwindingproperty from a bobbin, or reducing winding around a nip roller or acutter blade, can be obtained, and it may become possible to improveproductivity. Furthermore, it is possible to suppress the collapse ofthe cut fiber bundle or dispersion at a single fiber level thereof,thereby improving maintenance property at a predetermined bundle form.By this, because the fiber bundles are oriented in a plane direction ina mat sprayed with the cut fiber bundles, the mechanical properties maybe further improved.

According to the specific optimal partial separation processing, thefiber bundle can be continuously and stably slit, and the partiallyseparated fiber bundle with the optimal form can be produced easily andefficiently. In particular, even in a fiber bundle containing twist or afiber bundle of a large tow with a large number of single fibers, it ispossible to provide a method of producing a partially separated fiberbundle, enabling a continuous slit processing without worrying about theexchange life of a rotary blade. Furthermore, it becomes possible toprocess a continuous slitting of an inexpensive large tow, and it alsobecomes possible to reduce the material cost and the production cost ofa molded article.

Further, in the fiber-reinforced resin molding material, because ofcontaining a reinforcing fiber mat obtained by cutting and spraying theabove-described partially separated fiber bundle capable of exhibitingthe flowability during molding and the mechanical properties of a moldedarticle at a good balance, and a matrix resin, also in molding thinfiber bundles and thick fiber bundles can be mixed at a ratio within anoptimal range or at an optimal distribution state, securely theflowability during molding and the mechanical properties of a moldedarticle can be exhibited at a good balance.

Further, in the method of producing a fiber-reinforced resin moldingmaterial, it becomes possible to perform a series of steps [A] to [C]continuously in a single process, and a desired fiber-reinforced resinmolding material can be produced efficiently and smoothly, in addition,with an excellent productivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing an example of a partiallyseparated fiber bundle performed with separation processing to a fiberbundle.

FIGS. 2A and 2B show (A) a schematic plan view and (B) a schematic sideview, showing an example in which a separation means is penetrated intoa traveling fiber bundle.

FIGS. 3A and 3B show (A) a schematic plan view and (B) a schematic sideview, showing an example of a movement cycle in which a movingseparation means is penetrated into a fiber bundle.

FIGS. 4A and 4B show schematic explanatory views showing another exampleof a movement cycle in which a moving separation means is penetratedinto a fiber bundle.

FIGS. 5A-5C are is explanatory diagrams showing an example of a movementcycle in which a rotatable separation means is penetrated.

FIG. 6 is a process chart showing an example of a timing of a sizingagent application step in the method of producing a partially separatedfiber bundle.

FIG. 7 is a process chart showing an example of a timing of a sizingagent application step in the method of producing a partially separatedfiber bundle including a fiber bundle widening step.

FIG. 8 is a process chart showing an example of a timing of a sizingagent application step including a sizing agent applying step and adrying step in the method for producing a partially separated fiberbundle.

FIG. 9 is a process chart showing another example of a timing of asizing agent application step including a sizing agent applying step anda drying step in the method for producing a partially separated fiberbundle.

FIG. 10 is a process chart showing an example of a timing of a sizingagent application step including a sizing agent applying step and adrying step in the method for producing a partially separated fiberbundle including a fiber bundle widening step.

FIG. 11 is a process chart showing another example of a timing of asizing agent application step including a sizing agent applying step anda drying step in the method for producing a partially separated fiberbundle including a fiber bundle widening step.

FIG. 12 is a schematic diagram showing a method of producing afiber-reinforced resin molding material according to an example.

FIG. 13 is a schematic perspective view showing an example of obliquelycutting a partially separated fiber bundle with respect to itslengthwise direction.

EXPLANATION OF SYMBOLS

-   1: process for producing fiber-reinforced resin molding material-   2: partial separation step [A]-   3: matting step [B]-   4: resin impregnation step [C]-   5: creel-   6: reinforcing fiber bundle-   6 a: reinforcing fibers-   7: partially separated fiber bundle-   8: cutter unit-   8 a: cutting blade-   9: spraying mechanism-   10: reinforcing fiber mat-   11: thermosetting resin-   12: film-   13: belt-   14: resin impregnation roller-   15: fiber-reinforced resin molding material-   100: fiber bundle-   110: separation-processed section-   120: entanglement accumulation part-   130: not-separation-processed section-   140: fluff accumulation-   150: separation-processed part-   160: entangled part-   170: separation distance-   180: partially separated fiber bundle-   181: not-separation-processed part-   200: separation means-   210: projected part-   211: contact part-   220: rotatable separation means-   240: rotation shaft-   300: partial separation processing step-   301: fiber bundle widening step-   400: sizing agent application step-   401: sizing agent applying step-   402: drying step

DETAILED DESCRIPTION

Hereinafter, examples will be explained referring to the figures. Thisdisclosure is not limited in any way to the examples in the drawings.

First, the method of producing a partially separated fiber bundle willbe explained. FIG. 1 shows an example of a partially separated fiberbundle performed with separation processing to a fiber bundle, and FIG.2 shows an example of the separation processing. A method of producing apartially separated fiber bundle will be explained using FIG. 2. FIG. 2shows (A) a schematic plan view and (B) a schematic side view, showingan example in which a separation means is penetrated into a travelingfiber bundle. In the figure, a fiber bundle running direction A (arrow)is the lengthwise direction of a fiber bundle 100, which shows that thefiber bundle 100 is continuously supplied from a fiber bundle supplydevice that is not shown in the figure.

The separation means 200 is provided with a projected part 210 having aprojecting shape which is easy to be penetrated into the fiber bundle100, and which is penetrated into the traveling fiber bundle 100 tocreate a separation-processed part 150 approximately parallel to thelengthwise direction of the fiber bundle 100. It is preferred that theseparation means 200 is penetrated in a direction along the side surfaceof the fiber bundle 100. The side surface of the fiber bundle means asurface in the vertical direction in a sectional end when the section ofthe fiber bundle is a flat shape such as a laterally elongatedelliptical shape or a laterally elongated rectangular shape (forexample, corresponding to the side surface of the fiber bundle 100 shownin FIG. 2). Further, the number of projected parts 210 to be providedmay be one for each single separation means 200 or may be plural. Whenthere are a plurality of projected parts 210 in one separation means200, because the abrasion frequency of the projected part 210 decreases,it becomes possible to reduce the frequency of exchange. Furthermore, itis also possible to simul-taneously use a plurality of separation means200 depending upon the number of fiber bundles to be separated. It ispossible to arbitrarily dispose a plurality of projected parts 210 byarranging a plurality of separation means 200 in parallel, staggeringly,in shifted phases or the like.

When the fiber bundle 100 comprising a plurality of single fibers isdivided into separated bundles with a smaller number of fibers by theseparation means 200, since the plurality of single fibers aresubstantially not aligned in the fiber bundle 100 but there are manyportions interlaced at the single fiber level, entangled parts 160, inwhich the single fibers are interlaced in the vicinity of the contactparts 211 during the separation processing, may be formed.

“Forming the entangled part 160” means, for example, a case of forming(moving) the entanglement of single fibers with each other, which hasbeen previously present in the separation-processed section, on thecontact part 211 by the separation means 200, forming (producing) anaggregate, in which single fibers are newly interlaced, by theseparation means 200, and the like.

After creating the separation-processed part 150 in an arbitrary range,the separation means 200 is removed from the fiber bundle 100. By thisremoval, a separation-processed section 110 performed with separationprocessing is created, and at the same time as that, the entangled parts160 created as described above are accumulated in the end portion of theseparation-processed section 110, and an entanglement accumulation part120 accumulated with the entangled parts 160 is created. Further, fluffsgenerated from the fiber bundle during the separation processing areformed as a fluff accumulation 140 near the entanglement accumulationpart 120 at the time of the separation processing.

Thereafter, by penetrating the separation means 200 into the fiberbundle 100 again, the not-separation-processed section 130 is createdand a partially separated fiber bundle 180 is formed in which theseparation-processed sections 110 and the not-separation-processedsections 130 are disposed alternately along the lengthwise direction ofthe fiber bundle 100. In the partially separated fiber bundle 180, it ispreferred that the content of the not-separation-processed sections 130is set to 3% or more and 50% or less. The content of thenot-separation-processed sections 130 is defined as the rate of thetotal generation length of the not-separation-processed sections 130 ina unit length of the fiber bundle 100. If the content of thenot-separation-processed sections 130 is less than 3%, the processstability of the separation processing is deteriorated, the flowability,at the time when the partially separated fiber bundle 180 is cut and thecut bundles are sprayed and used as an intermediate base material offiber bundles of discontinuous fibers, becomes poor, and if the contentexceeds 50%, the mechanical properties of a molded article molded usingit decrease.

Further, as the length of each section, the length of theseparation-processed section 110 is preferably 30 mm or more and 1,500mm or less, and the length of the not-separation-processed section 130is preferably 1 mm or more and 150 mm or less.

The running speed of the fiber bundle 100 is preferably a stable speedwith little fluctuation, more preferably a constant speed.

The separation means 200 is not particularly limited as long as thedesired result can be achieved, and it is preferable to have a shapelike a sharp shape such as a metal needle or a thin plate. As theseparation means 200, it is preferred that a plurality of separationmeans 200 are provided in the width direction of the fiber bundle 100which is performed with the separation processing, and the number ofseparation means 200 can be arbitrarily selected depending upon thenumber of single fibers F forming the fiber bundle 100 to be carried outwith the separation processing. It is preferred that the number ofseparation means 200 is (F/10,000−1) or more and less than (F/50−1) withrespect to the width direction of the fiber bundle 100. If it is lessthan (F/10,000−1), improvements in mechanical properties are hardlyexhibited when a reinforcing fiber composite material is made in a laterstep, and if it is (F/50−1) or more, there is a possibility of yarnbreakage or fluffing during the separation processing.

The fiber bundle 100 is not particularly limited in fiber kind as longas it is a fiber bundle comprising a plurality of single fibers. In thisconnection, it is preferred to use reinforcing fibers, and inparticular, the kind thereof is preferably at least one selected fromthe group consisting of carbon fibers, aramide fibers and glass fibers.These may be used solely, or two or more of them can be used together.Among those, carbon fibers are particularly preferable because it ispossible to provide a composite material light in weight and excellentin strength. As the carbon fibers, any one of PAN type and pitch typemay be used, and the average fiber diameter thereof is preferably 3 to12 μm, and more preferably 6 to 9 μm.

In carbon fibers, usually, a fiber bundle obtained by bundling about3,000 to 60,000 single fibers made of continuous fibers is supplied as awound body (package) wound around a bobbin. Although it is preferredthat the fiber bundle is untwisted, it is also possible to use a twistedstrand, and it is applicable even if twisting occurs during conveyance.There is no restriction on the number of single fibers, and when aso-called large tow having a large number of single fibers is used,since the price per unit weight of the fiber bundle is inexpensive, asthe number of single fibers increases, the cost of the final product canbe reduced, and such a condition is preferred. Further, as a large tow,a so-called doubling form in which fiber bundles are wound together in aform of one bundle may be employed.

When reinforcing fibers are used, it is preferred that they are surfacetreated for the purpose of improving the adhesive property with a matrixresin used when made to a reinforcing fiber composite material. As themethod for the surface treatment, there are an electrolytic treatment,an ozone treatment, a ultraviolet treatment and the like. Further, asizing agent may be applied for the purpose of preventing fluffing ofthe reinforcing fibers, improving convergence property of thereinforcing fiber strand, improving adhesive property with the matrixresin and the like. However, this application of the sizing agent isperformed at a step different from the sizing agent applicationperformed at an arbitrary timing in the production process of thepartially separated fiber bundle, that is described later. As the sizingagent, though not particularly limited, a compound having a functionalgroup such as an epoxy group, a urethane group, an amino group, acarboxyl group or the like can be used, and as such a compound, one typeor a combination of two or more types may be used. Also with respect tothe sizing agent applied at an arbitrary timing in the productionprocess of the partially separated fiber bundle, that is describedlater, similar one can be used.

The fiber bundle is preferably in a state of being bundled in advance.“The state being bundled in advance” indicates, for example, a state inwhich the single fibers forming the fiber bundle are bundled byentanglement with each other, a state in which the fibers are convergedby a sizing agent applied to the fiber bundle, or a state in which thefibers are converged by twist generated in a process of manufacturingthe fiber bundle.

Our methods are not limited to when the fiber bundle travels, and asshown in FIG. 3, a method may be also employed wherein the separationmeans 200 is penetrated into the fiber bundle 100 being in a stationarystate (arrow (1)), then, while the separation means 200 is traveledalong the fiber bundle 100 (arrow (2)), the separation-processed part150 is created, and thereafter, the separation means 200 is removed(arrow (3)). Thereafter, as shown in FIG. 4(A), the separation means 200may be returned to the original position (arrow (4)) after the fiberbundle 100 having been in a stationary state is moved by a constantdistance at timings shown by arrows (3) and (4), or as shown in FIG.4(B), without moving the fiber bundle 100, the separation means 200 maybe traveled until it passes through the entanglement accumulation part120 (arrow (4)).

When the fiber bundle 100 is subjected to separation processing while itis moved by a constant distance, as shown in FIG. 3(B) or FIG. 4(A), thecontrol is performed in a method preferably so that a separationprocessing time during being penetrated with the separation means 200(the time of operation indicated by arrow (2)) and a time from beingremoved with the separation means 200 to being penetrated again into thefiber bundle (the time of operation indicated by arrows (3), (4) and(1)) are controlled. In this example, the moving direction of theseparation means 200 is the repetition of (1) to (4) in the figure.

Further, when the fiber bundle 100 is not moved and the separationprocessing is performed while moving the separation means 200 until theseparation means 200 passes through the entanglement accumulation part120, as shown in FIG. 4(B), the control is performed in another methodpreferably so that a separation processing time during being penetratedwith the separation means 200 (the time of operation indicated by arrow(2) or arrow (6)) and a time from being removed with the separationmeans 200 to being penetrated again into the fiber bundle (the time ofoperation indicated by arrows (3), (4) and (5) or by arrows (3), (4) and(1)) are controlled. Also in this example, the moving direction of theseparation means 200 is the repetition of (1) to (4) in the figure.

Thus, by the separation means 200, the separation-processed sections andthe not-separated-processed sections are alternatively formed, and apartially separated fiber bundle is produced so that thenot-separation-processed sections have a ratio within a predeterminedrange with respect to the unit length of the fiber bundle.

Depending upon the entanglement state of single fibers forming the fiberbundle 100, without securing a not-separation-processed section havingan arbitrary length (for example, in FIG. 2, after creating theseparation-processed section 110, creating a next separation-processedpart 150 with securing a not-separation-processed section 130 having aconstant length), it is possible to restart separation processingsubsequently from the vicinity of the terminal end portion of theseparation-processed section. For example, as shown in FIG. 4(A), whenthe separation processing is performed while intermittently moving thefiber bundle 100, after the separation means 200 performs the separationprocessing (arrow (2)), by setting the moving length of the fiber bundle100 to be shorter than the length of the separation processing performedimmediately before, the position (arrow (1)) where the separation means200 is to be penetrated once again can be overlapped with theseparation-processed section performed with the separation processingimmediately before. On the other hand, as shown in FIG. 4(B), incarrying out the separation processing while moving the separation means200 itself, after once removing the separation means 200 (arrow (3)),without moving it at a constant length (arrow (4)), the separation means200 can be penetrated into the fiber bundle again (arrow (5)).

In such a separation processing, when a plurality of single fibersforming the fiber bundle 100 are interlaced with each other, since thesingle fibers are not substantially aligned in the fiber bundle, even ifthe separation means 200 is penetrated at the same position as theposition where the separation processing has been already performed oras the position where the separation means 200 has been removed, in thewidth direction of the fiber bundle 100, the position to be penetratedis easily shifted with respect to the single fiber level, and theseparation processed state (gap) is not continued from theseparation-processed section formed immediately before and they canexist as separation-processed sections different from each other.

The length of the separation-processed section obtained per oneseparation processing (separation distance 170) is preferably 30 mm ormore and less than 1,500 mm, although it depends upon the entanglementstate of single fibers of the fiber bundle performed with the separationprocessing. If it is less than 30 mm, the effect according to theseparation processing is insufficient, and if it is 1,500 mm or more,depending upon the reinforcing fiber bundle, there is a possibility ofoccurrence of yarn breakage or fluffing.

Further, when a plurality of separation means 200 are provided, it isalso possible to provide a plurality of alternately formedseparation-processed sections and not-separation-processed sectionsapproximately parallel to each other with respect to the width directionof the fiber bundle. In this example, as aforementioned, it is possibleto arbitrarily dispose a plurality of projected parts 210 by arranging aplurality of separation means 200 in parallel, staggeringly, in shiftedphases or the like.

Furthermore, each of the plurality of projected parts 210 can also becontrolled independently. Although the details will be described later,it is also preferred that the individual projected parts 210independently perform separation processing by the time required for theseparation processing or the pressing force detected by the projectedpart 210.

The fiber bundle is unwound from an unwinding device (not shown) or thelike disposed on the upstream side in the fiber bundle travelingdirection for unwinding the fiber bundle. As the unwinding direction ofthe fiber bundle, although a laterally unwinding system for pulling outin a direction perpendicular to the axis of rotation of a bobbin and alongitudinally unwinding system for pulling out in the same direction asthe axis of rotation of the bobbin (paper tube) are considered, thelaterally unwinding system is preferred in consideration that in thatsystem there are few unwinding twists.

Further, with respect to the installation posture of the bobbin at thetime of unwinding, it can be installed in an arbitrary direction. Inparticular, when, in a state where the bobbin is pierced through thecreel, the end surface of the bobbin on the side not being the creelrotation shaft fixed surface is directed in a direction other than thehorizontal direction, it is preferred that the fiber bundle is held in astate where a constant tension is applied to the fiber bundle. Whenthere is no constant tension in the fiber bundle, it is considered thatthe fiber bundle falls from and is separated from a package (a windingbody in which the fiber bundle is wound on the bobbin), or that a fiberbundle separated from the package winds around the creel rotation shaft,whereby unwinding becomes difficult.

Further, as a method of fixing the rotation shaft of the unwoundpackage, in addition to the method of using a creel, a surface unwindingmethod is also applicable wherein a package is placed on two rollersarranged in parallel with each other at a state in parallel with the twoparallel rollers, and the package is rolled on the arranged rollers tounwind a fiber bundle.

Further, in unwinding using a creel, a method of applying a tension tothe unwound fiber bundle by applying a brake to the creel by putting abelt around the creel, fixing one end of the belt, and hanging theweight or pulling with a spring at the other end or the like, isconsidered. In this example, varying the braking force depending uponthe winding diameter is effective as means for stabilizing the tension.

Furthermore, to adjust the number of single fibers after separationprocessing, a method of widening the fiber bundle and a method foradjustment by a pitch of a plurality of separation means arranged in thewidth direction of the fiber bundle can be employed. By making the pitchof the separation means smaller and providing a larger number ofseparation means in the width direction of the fiber bundle, it becomespossible to perform a so-called thin bundle separation processing intothin bundles each having fewer single fibers. Further, it is alsopossible to adjust the number of single fibers even by widening thefiber bundle before separation processing and applying separationprocessing to the widened fiber bundle with a larger number ofseparation means without narrowing the pitch of the separation means.

The term “widening” means a processing of expanding the width of thefiber bundle 100. The widening method is not particularly restricted,and it is preferred to use a vibration widening method of passingthrough a vibration roll, an air widening method of blowing compressedair, or the like.

The separation-processed part 150 is formed by repeating penetration andremoval of the separation means 200. At that time, it is preferred toset the timing of penetrating again by the time passed after removingthe separation means 200. Further, also it is preferred to set thetiming of removing again by the time passed after penetrating theseparation means 200. By setting the timing of penetrating and/orremoving by time, it becomes possible to create the separation-processedsection 110 and the not-separation-processed section 130 atpredetermined distance intervals, and it also becomes possible toarbitrarily determine the ratio between the separation-processed section110 and the not-separation-processed section 130. Further, although thepredetermined time intervals may be always the same, it is also possibleto change the intervals in accordance with circumstances such asincreasing or shortening the intervals depending upon the distance atwhich the separation processing has been progressed, or changing theintervals depending upon the state of the fiber bundle at respectivetimes, for example, shortening the predetermined time intervals in casewhere there is little fluffing or entanglement of single fibers in theoriginal fiber bundle or the like.

When the separation means 200 is penetrated into the fiber bundle 100,since the created entangled part 160 continues to press the projectedpart 210 in accordance with the progress of the separation processing,the separation means 200 receives a pressing force from the entangledpart 160.

As aforementioned, a plurality of single fibers are not substantiallyaligned in the fiber bundle 100 but in most portions they are interlacedwith each other at the single fiber level and, further, in thelengthwise direction of the fiber bundle 100, there is a possibilitywhere there exist a portion with many entanglements and a portion withfew entanglements. In the portion with many entanglements of singlefibers, the rise of the pressing force at the time of separationprocessing becomes fast and, conversely, in the portion with fewentanglements of single fibers, the rise of the pressing force becomesslow. Therefore, it is preferred that the separation means 200 isprovided with a pressing force detection means for detecting a pressingforce from the fiber bundle 100.

Further, since the tension of the fiber bundle 100 may change before andafter the separation means 200, at least one tension detection means fordetecting the tension of the fiber bundle 100 may be provided in thevicinity of the separation means 200, or a plurality of them may beprovided and a difference in tension may be calculated. These means fordetecting the pressing force, the tension and the tension difference maybe provided individually, or may be provided in a form of anycombination thereof. The tension detection means for detecting thetension is disposed preferably 10 to 1,000 mm apart from the separationmeans 200 in at least one of the front and rear of the fiber bundle 100along the lengthwise direction of the fiber bundle 100.

It is preferred that the removal of the separation means 200 iscontrolled in accordance with each detected value of these pressingforce, tension and tension difference. It is further preferred tocontrol removing the separation means 200 when the detected valueexceeds an arbitrarily set upper limit value accompanying with the riseof the detected value. In the pressing force and the tension, it ispreferred to set the upper limit value to 0.01 to 1 N/mm, and in thetension difference to 0.01 to 0.8 N/mm. The upper limit value may bevaried within a range of ±10% depending upon the state of the fiberbundle. The unit (N/mm) of the pressing force, the tension and thetension difference indicates force acting per the width of the fiberbundle 100.

If lowering than the range of the upper limit value of the pressingforce, the tension or the tension difference, because immediately afterpenetrating the separation means 200 the pressing force, the tension orthe tension difference reaches a value to be removed with the separationmeans 200, a sufficient separation processing distance cannot beobtained, the separation-processed section 110 becomes too short and,therefore, the fiber bundle performed with separation processing triedto be obtained cannot be obtained. On the other hand, if exceeding therange of the upper limit value, because after penetrating the separationmeans 200 cutting of the single fibers in the fiber bundle 100 increasesbefore the pressing force, the tension or the tension difference reachesa value to be removed with the separation means 200, defects such asprojecting of the fiber bundle having been performed with separationprocessing in a shape like a split end or increase of generated fluffs,are likely to occur. The projected split end may be wrapped around aroll being served to the conveyance, or the fluffs are accumulated on adrive roll to cause slipping in the fiber bundle, and the like, andthus, a conveyance failure tends to be caused.

Different from when the timing of removal of the separation means 200 iscontrolled with time, in detecting the pressing force, the tension andthe tension difference, because the separation means 200 is removedbefore a force enough to cut the fiber bundle 100 is applied during theseparation processing, an unreasonable force is not applied to the fiberbundle 100, and continuous separation processing becomes possible.

Furthermore, to obtain the fiber bundle 100 which has a longseparation-processed section 110 and a stable shape of the entanglementaccumulation part 120 in the lengthwise direction, while suppressing theoccurrence of branching or fluffing like a partial cutting of the fiberbundle 100, it is preferred that the pressing force is controlled to0.04 to 0.4 N/mm, the tension is controlled to 0.02 to 0.2 N/mm, and thetension difference is controlled to 0.05 to 0.5 N/mm.

It is also preferred to provide an imaging means for detecting thepresence of a twist of the fiber bundle 100 at 10 to 1,000 mm in atleast one of the front and rear of the fiber bundle 100 along thelengthwise direction of the fiber bundle 100 from the separation means200 having been penetrated into the fiber bundle 100. By this imaging,the position of the twist is specified beforehand, and it is controlledto not penetrate the separation means 200 into the twist, thereby makingit possible to prevent a mistake in penetration. Further, by removingthe separation means 200 when the twist approaches the penetratedseparation means 200, that is, by controlling to not penetrate theseparation means 200 into the twist, it is possible to prevent narrowingin width of the fiber bundle 100. A mistake in penetration means thatthe separation means 200 is penetrated into the twist, the fiber bundle100 is only pushed and moved in the penetrating direction of theseparation means 200, and the separation processing is not performed.

In a configuration in which a plurality of separation means 200 arepresent in the width direction of the fiber bundle 100 and are arrangedat equal intervals, if the width of the fiber bundle 100 varies, becausethe number of single fibers having been performed with separationprocessing also varies, there is a possibility that a separationprocessing with a stable number of single fibers cannot be performed.Further, if the twist is forcibly performed with separation processing,because the fiber bundle 100 is cut at the single fiber level togenerate a large amount of fluffs, the shape of the entanglementaccumulation part 120 in which the entangled parts 160 are accumulatedbecomes large. If the large entanglement accumulation part 120 is left,it is easily caught by the fiber bundle 100 unwound from the roll.

When the twist of the fiber bundle 100 is detected, other than theabove-described control to not penetrate the separation means 200 intothe twist, the traveling speed of the fiber bundle 100 may be changed.Concretely, after the twist is detected, the traveling speed of thefiber bundle 100 is increased at the timing when the separation means200 is being removed from the fiber bundle 100 until the twist passesthrough the separation means 200, thereby efficiently avoiding thetwist.

Further, an image calculation processing means for calculating the imageobtained by the imaging means may be further provided, and a pressingforce control means for controlling the pressing force of the separationmeans 200 based on the calculation result of the image calculationprocessing means may be further provided. For example, when the imagecalculation processing means detects a twist, it is possible to improvethe passing ability of the twist when the separation means passes thetwist. Concretely, it is preferred to detect the twist by the imagingmeans and to control the separation means 200 so that the pressing forceis decreased from just before the projected part 210 comes into contactwith the detected twist to the time when the projected part 210 passestherethrough. When the twist is detected, it is preferred to reduce itto 0.01 to 0.8 time the upper limit value of the pressing force. When itis below this range, substantially the pressing force cannot bedetected, it becomes difficult to control the pressing force, or itbecomes necessary to enhance the detection accuracy of the controldevice itself. Further, when it exceeds this range, the frequency of theseparation processing performed to the twist is increased and the fiberbundle becomes narrow.

It is also preferred to use a rotatable separation means 220 rotatableas the separation means other than simply penetrating the separationmeans 200 having the projected part 210 into the fiber bundle 100. FIG.5 is an explanatory view showing an example of a movement cycle in whicha rotatable separation means is penetrated. The rotatable separationmeans 220 has a rotation mechanism having a rotation axis 240 orthogonalto the lengthwise direction of the fiber bundle 100, and the projectedpart 210 is provided on the surface of the rotation shaft 240. As thefiber bundle 100 travels along the fiber bundle running direction B(arrow) in the figure, the projected parts 210 provided in the rotatableseparation means 220 are penetrated into the fiber bundle 100 and theseparation processing is started. Although omitted in the figure, it ispreferred that the rotatable separation means 220 has a pressing forcedetection mechanism and a rotation stop position holding mechanism.Until a predetermined pressing force acts on the rotatable separationmeans 220 by the both mechanisms, the rotation stop position ismaintained at the position shown in FIG. 5(A) and the separationprocessing is continued. When exceeding the predetermined pressingforce, for example, when an entangled part 160 is caused at the positionof the projected part 210, the rotatable separation means 220 starts torotate as shown in FIG. 5(B). Thereafter, as shown in FIG. 5(C), theprojected part 210 (black circle mark) is removed from the fiber bundle100, and the next projected part 210 (white circle mark) is penetratedinto the fiber bundle 100. The shorter the operation shown in FIGS. 5(A)to 5(C) is, the shorter the not-separation-processed section becomesand, therefore, in case where it is attempted to increase the proportionof separation-processed sections, it is preferred to shorten theoperation shown in FIGS. 5(A) to 5(C).

By arranging the projected parts 210 more in the rotatable separationmeans 220, it is possible to obtain a fiber bundle 100 with a highproportion of separation processing and to extend the life of therotatable separation means 220. A fiber bundle with a high proportion ofseparation processing means a fiber bundle obtained by lengthening theseparation-processed length within the fiber bundle, or a fiber bundlein which the frequency of occurrence of the separation-processedsections and the not-separation-processed sections is increased.Further, as the number of the projected parts 210 provided in onerotatable separation means increases, the lifetime can be lengthened byreducing the frequency of contact of the projected parts 210 with thefiber bundle 100 and wear of the projected parts 210. As for the numberof projected parts 210 to be provided, it is preferred to arrange 3 to12 pieces at equal intervals on the disk-shaped outer edge, morepreferably 4 to 8 pieces.

Thus, when attempting to obtain a fiber bundle 100 with a stable fiberbundle width while giving priority to the proportion of separationprocessing and the life of the projected parts, it is preferred that therotatable separation means 220 has an imaging means for detecting atwist. Concretely, during normal operation until the imaging meansdetects the twist, the rotatable separation means 220 intermittentlyrepeats the rotation and the stop to perform the separation processing,and when the twist is detected, the rotational speed of the rotatableseparation means 220 is increased from the speed at the normal timeand/or the stop time is shortened, thereby stabilizing the fiber bundlewidth.

It is also possible to control the stop time to zero, that is, tocontinue the rotation without stopping.

Further, other than the method of repeating the intermittent rotationand stopping of the rotatable separation means 220, the rotatableseparation means 220 may always continue to rotate. At that time, it ispreferred to make either one of the traveling speed of the fiber bundle100 and the rotational speed of the rotatable separation means 220relatively faster or slower. When the speeds are the same, althoughseparation-processed sections can be formed because the operation ofpenetrating/removing the projected part 210 into/from the fiber bundle100 is performed, since the separation processing operation acting onthe fiber bundle 100 is weak, there is a possibility that the separationprocessing is not be performed sufficiently. Further, when any one ofthe speeds is too fast or too slow, the number of times the fiber bundle100 and the projected parts 210 come in contact with each otherincreases, there is a possibility that yarn breakage may occur due torubbing, which causes to be inferior in continuous productivity.

A reciprocating movement mechanism of performing penetrating andremoving of the separation means 200 or the rotatable separation means220 by reciprocating movement of the separation means 200 or therotatable separation means 220 may be further provided. Further, it isalso preferred to further provide a reciprocating movement mechanism toreciprocate the separation means 200 and the rotatable separation means220 along the feed direction of the fiber bundle 100. For thereciprocating movement mechanism, it is possible to use a linear motionactuator such as a compressed-air or electric cylinder or slider.

The number of separation-processed sections in using reinforcing fibersfor fiber bundles is preferably at least (F/10,000−1) or more and lessthan (F/50−1) in a certain region in the width direction. F is the totalnumber of single fibers forming the fiber bundle to be performed withseparation processing. By providing the separation-processed sectionscontrolled in number thereof at least at (F/10,000−1) or more in acertain region in the width direction, when the partially separatedfiber bundle is cut to a predetermined length to be made into adiscontinuous fiber reinforced composite material, because the endportion of the reinforcing fiber bundle in the discontinuous fiberreinforced composite material is finely divided, a discontinuous fiberreinforced composite material having excellent mechanical properties canbe obtained. Further, when the partially separated fiber bundle is usedas continuous fibers without cutting it, when a reinforcing fibercomposite material is made by impregnating a resin or the like thereintoin a later process, a starting point for resin impregnation into thereinforcing fiber bundle is made from a region included with manyseparation-processed sections, the molding time can be shortened andvoids and the like in the reinforcing fiber composite material can bereduced. By controlling the number of separation-processed sections toless than (F/50−1), the obtained partially separated fiber bundlebecomes hard to cause yarn breakage, and the decrease of mechanicalproperties when made into a fiber-reinforced composite material can besuppressed.

If the separation-processed sections are provided with periodicity orregularity in the lengthwise direction of the fiber bundle 100, when thepartially separated fiber bundle is cut to a predetermined length in alater process to make discontinuous fibers, it is possible to easilycontrol to a predetermined number of separated fiber bundles.

Next, in the production of a specified partially separated fiber bundle,performed with the above-described specified optimal partial separationprocessing, application of a sizing agent performed at an arbitrarytiming in the production process of the partially separated fiber bundlewill be explained.

The means of applying a sizing agent is not particularly limited, andany known means can be used. For example, it is commonly carried outthat a sizing treatment liquid in which a sizing agent is dissolved(including dispersed) in a solvent (including a dispersion medium incase of dispersing) is prepared, and after the sizing treatment liquidis applied to a fiber bundle, by drying, vaporizing and removing thesolvent, the sizing agent is applied to the fiber bundle. As describedlater in detail, a partial separation processing or a fiber bundlewidening processing may be performed between this applying step and thedrying step.

As a method of applying a sizing treatment liquid to the fiber bundle,for example, there are a method of immersing the fiber bundle in asizing treatment liquid through a roller, a method of contacting thefiber bundle to a roller attached with a sizing treatment liquid, amethod of making a sizing treatment liquid into a mist state and blowingit on the fiber bundle and the like. In this example, it is preferred tocontrol sizing treatment liquid concentration, temperature, threadtension and the like so that the adhesion amount of the sizing agenteffective ingredient to the fiber bundle uniformly adheres within aproper range. Further, it is more preferred to excite the fiber bundlewith ultrasonic waves at the time of sizing agent application.

Although the adhesion amount of the sizing agent is not particularlylimited, the sizing agent is preferably 0.01 to 10% by weight in 100% byweight of the fiber bundle after sizing agent application. When a sizingagent is applied to an original fiber bundle, it is preferred that thetotal adhesion amount of sizing agent is within the above-describedrange.

Further, although the drying temperature and the drying time should beadjusted depending upon the ingredients and the adhesion amount of thesizing agent, it is preferred to shorten the time required for completeremoval and drying of the solvent used for the sizing agent application,and from the viewpoint of preventing thermal degradation of the sizingagent, to control the drying temperature preferably at 150° C. or moreand 350° C. or less, and more preferably at 180° C. or more and 250° C.or less.

Next, the timing of the sizing agent application will be explained indetail.

FIG. 6 shows a timing example of a sizing agent application step in theproduction process of the partially separated fiber bundle in the methodof producing the partially separated fiber bundle. In FIG. 6, in theprocess in which the fiber bundle 100 is formed into the partiallyseparated fiber bundle 180 through the partial separation processingstep 300, a pattern A in which the sizing agent application step 400 iscarried out before the partial separation processing step 300 and apattern B in which it is carried out after the partial separationprocessing step 300 are shown. Any timing of either pattern A or patternB is possible.

FIG. 7 shows a timing example of the sizing agent application step 400in the production process of the partially separated fiber bundle in themethod for producing the partially separated fiber bundle including afiber bundle widening step 301. In FIG. 7, in the process in which thefiber bundle 100 is formed into the partially separated fiber bundle 180through the fiber bundle widening step 301 and the partial separationprocessing step 300 in this order, a pattern C in which the sizing agentapplication step 400 is carried out before the fiber bundle wideningstep 301, a pattern D in which it is carried out between the fiberbundle widening step 301 and the partial separation processing step 300,and a pattern E in which it is carried out after the partial separationprocessing step 300, are shown. Although any timing of pattern C,pattern D and pattern E is possible, the timing of pattern D is mostpreferable from the viewpoint that optimal partial separation processingcan be achieved.

FIG. 8 shows a timing example of a sizing agent application stepincluding a sizing agent applying step and a drying step in theproduction process of the partially separated fiber bundle in the methodfor producing the partially separated fiber bundle. The sizing agentapplication step 400 includes a sizing agent applying step 401 and adrying step 402, and in FIG. 8, in the process in which the fiber bundle100 is formed into the partially separated fiber bundle 180 through thepartial separation processing step 300, a pattern F in which the sizingagent application step 400 including these sizing agent applying step401 and drying step 402 is carried out before the partial separationprocessing step 300 and a pattern G in which it is carried out after thepartial separation processing step 300 are shown. Any timing of eitherpattern F or pattern G is possible. The pattern G is substantially thesame as the pattern B in FIG. 6.

FIG. 9 shows another timing example of a sizing agent application stepincluding a sizing agent applying step and a drying step in theproduction process of the partially separated fiber bundle in the methodof producing the partially separated fiber bundle. In the pattern H inthe timing example shown in FIG. 9, the sizing agent applying step 401and the drying step 402 in the sizing agent application step 400 areseparated and performed at different timings. The sizing agent applyingstep 401 is performed before the partial separation processing step 300and the drying step 402 is performed after the partial separationprocessing step 300.

FIG. 10 shows a timing example of a sizing agent application stepincluding a sizing agent applying step and a drying step in the methodof producing the partially separated fiber bundle including a fiberbundle widening step. In the process in which the fiber bundle 100 isformed into the partially separated fiber bundle 180 through the fiberbundle widening step 301 and the partial separation processing step 300in this order, the sizing agent applying step 401 of the sizing agentapplication step is performed before the fiber bundle widening step 301,and with respect to the drying step 402, a pattern I in which it iscarried out between the fiber bundle widening step 301 and the partialseparation processing step 300 and a pattern J in which it is carriedout after the partial separation processing step 300 are shown.

FIG. 11 shows another timing example of a sizing agent application stepincluding a sizing agent applying step and a drying step in the methodof producing the partially separated fiber bundle including a fiberbundle widening step. In the process in which the fiber bundle 100 isformed into the partially separated fiber bundle 180 through the fiberbundle widening step 301 and the partial separation processing step 300in this order, a pattern K is shown in which the sizing agent applyingstep 401 of the sizing agent application step is performed between thefiber bundle widening step 301 and the partial separation processingstep 300, and the drying step 402 is performed after the partialseparation processing step 300.

Thus, in the method of producing a partially separated fiber bundle, itis possible to apply a sizing agent at various timings.

Next, the fiber-reinforced resin molding material will be explained.

The fiber-reinforced resin molding material contains a reinforcing fibermat obtained by cutting/spraying the above-described partially separatedfiber bundle and a matrix resin.

The average fiber length of the cut-off partially separated fiber bundleis preferably 5 to 100 mm, and more preferably 10 to 80 mm. Thedistribution of the fiber length may be a distribution of a single-kindfiber length or a mixture of two or more kinds.

Further, the matrix resin is not particularly restricted, and any of athermosetting resin and a thermoplastic resin can be used, and it can beappropriately selected within a range that does not greatly deterioratethe mechanical properties as a molded article. For example, in athermosetting resin, a vinyl ester resin, an epoxy resin, an unsaturatedpolyester resin, a phenol resin, an epoxy acrylate resin, a urethaneacrylate resin, a phenoxy resin, an alkyd resin, a urethane resin, amaleimide resin, a cyanate resin or the like can be used. Among them,any one of vinyl ester resin, epoxy resin, unsaturated polyester resin,phenol resin, or a mixture thereof is preferred. Further, in athermoplastic resin, polyolefin-based resins such as polyethylene resinand polypropylene resin, polyamide-based resins such as nylon 6 resinand nylon 6,6 resin, polyester-based resins such as polyethyleneterephthalate resin and polybutylene terephthalate resin, apolyphenylene sulfide resin, a polyether ketone resin, a polyethersulfone resin, an aromatic polyamide resin or the like can be used.Among them, any one of a polyamide resin, a polypropylene resin and apolyphenylene sulfide resin is preferred. A thermosetting resin can beused more preferably from the viewpoint of impregnating property of thematrix resin and applicability to the impregnating step.

FIG. 12 shows a method of producing a fiber-reinforced resin moldingmaterial according to an example. In FIG. 12, symbol 1 denotes the wholeof a process of producing a fiber-reinforced resin molding materialcontaining at least a reinforcing fiber mat and a matrix resin, whereinthe production process 1 comprises at least a partial separation step[A] 2 for obtaining a partially separated fiber bundle 7 in whichseparation-processed parts separated into a plurality of bundles andnot-separation-processed parts are alternately formed along thelengthwise direction of the reinforcing fiber bundle comprising aplurality of single fibers, and for applying a sizing agent at anarbitrary timing of the step as describe above, a matting step [B] 3 toobtain a reinforcing fiber mat 10 by cutting the partially separatedfiber bundle 7 and spraying the cut bundles, and a resin impregnationstep [C] 4 in which the reinforcing fiber mat 10 is impregnated with amatrix resin (thermosetting resin 11 in this example).

A reinforcing fiber bundle 6 composed of reinforcing fibers 6 a of aplurality of single fibers fed out from a plurality of creels 5 issupplied to the partial separation step [A] 2, partial separationprocessing is carried out in the step 2 as aforementioned, the partiallyseparated fiber bundle 7 is manufactured. The manufactured partiallyseparated fiber bundle 7 is subsequently (continuously) supplied to thematting step [B] 3, where it is cut into discontinuous fiber bundles bya cutter unit 8 in the step 3, and thereafter, the cut bundles aresprayed through a spraying mechanism 9, for example, on a belt 13 beingcirculated such that a reinforcing fiber mat 10 is formed. Thisreinforcing fiber mat 10 is impregnated with a thermosetting resin 11 asa matrix resin, and in this example, the resin impregnation in the resinimpregnation step [C] 4 is accelerated such that the reinforcing fibermat 10 and the supplied thermosetting resin 11 to be impregnated arenipped films 12 sequentially supplied to both upper and lower sides ofthe reinforcing fiber mat 10, and at the nipped state, they are pressed,for example, between a plurality of resin impregnation rollers 14. Thereinforcing fiber mat 10 impregnated with the matrix resin is folded asshown in the figure or wound as a continuous sheet-like fiber-reinforcedresin molding material 15 and, thus, a series of continuousfiber-reinforced resin molding material production process 1 iscompleted. The fiber-reinforced resin molding material 15 is produced,for example, as a sheet molding compound (SMC).

Thus, since first a partially separated fiber bundle 7 is manufactured,the partially separated fiber bundle 7 is cut and sprayed to prepare areinforcing fiber mat 10 derived from the partially separated fiberbundle, and thereinto the matrix resin 11 is impregnated to obtain thefiber-reinforced resin molding material 15, when cutting and sprayingthe partially separated fiber bundle 7 to prepare the reinforcing fibermat 10 as an intermediate base material of fiber bundles ofdiscontinuous fibers, it becomes possible to make thin fiber bundles andthick fiber bundles present at a mixed condition within a range of anoptimum ratio, and in the fiber-reinforced resin molding material 15impregnated with matrix resin 11 thereinto, it becomes possible toexhibit the flowability during molding and the mechanical properties ofa molded article at a good balance. In particular, in the manufacturingprocess of the partially separated fiber bundle 7, as described above,the fiber bundle can be stably slit continuously, and the partiallyseparated fiber bundle 7 in an optimum form can be easily andefficiently produced. Especially, even in a fiber bundle containingtwist or a fiber bundle of a large tow having a large number of singlefibers, a continuous slit processing becomes possible without worryingabout exchange life of a rotary blade. In addition, a continuous slitprocessing of an inexpensive large tow becomes possible, whereby it maybecome possible to reduce the material cost and production cost of afinally molded article.

From the viewpoint that it is possible to produce a desiredfiber-reinforced resin molding material 15 efficiently, smoothly, andwith excellent productivity in the above-described production process 1of the fiber-reinforced resin molding material, an example is shown as apreferred example wherein a series of the steps [A] to [C] are carriedout continuously in one process, but it is not necessary to continuouslycarry out the series of the steps [A] to [C] in one process, forexample, the partially separated fiber bundle obtained through the step[A] may be wound up once and then subjected to the step [B].

Further, when cutting the partially separated fiber bundle 7 in thematting step [B] 3 as shown in FIG. 12, it is also preferred to cut thepartially separated fiber bundle 7 at an angle θ (0<θ<90°) with respectto the lengthwise direction of the fiber bundle 7. For example, as shownin FIG. 13, with a cutting blade 8 a inclined at an angle θ (0<θ<90°)with respect to the lengthwise direction of the partially separatedfiber bundle 7 (running direction of the fiber bundle in the figure),the partially separated fiber bundle 7 is cut. In this way, the chanceof the cutting line by the cutting blade 8 a to extend over theseparation-processed section 150 and the not-separation-processed part181 increases, and when cutting the partially separated fiber bundle 7to make the fiber bundle of the discontinuous fibers, because the chancethat the discontinuous fiber bundle is formed only from thenot-separation-processed part 181 decreases, it becomes possible to forma mat comprising discontinuous fiber bundles with a thinner size. In afiber-reinforced resin molding material using such a mat, it becomespossible to particularly improve the mechanical properties of a moldedarticle.

EXAMPLES

Next, examples and comparative examples will be explained. Thisdisclosure is not limited in any way to the examples and comparativeexamples.

Raw Material

Fiber Bundle [A-1]:

A continuous carbon fiber bundle (“PANEX (registered trademark) 35,”supplied by ZOLTEK CORPORATION) having a fiber diameter of 7.2 μm, atensile modulus of elasticity of 240 GPa, and a number of single fibersof 50,000 was used.

Sizing Agent [s-1]:

A reactive urethane resin emulsion (“SuperFlex (registered trademark)R5000,” supplied by DKS Co., Ltd.) was used.

Matrix Resin [M-1]:

A resin compound prepared by sufficiently mixing and stirring 100 partsby weight of a vinyl ester resin (“DELAKEN (registered trademark) 790,”supplied by Dow. Chemical Co., Ltd.), 1 part by weight of tert-butylperoxybenzoate (“Perbutyl (registered trademark) Z,” supplied by NOFCORPORATION) as a curing agent, 4 parts by weight of magnesium oxide(MgO #40, supplied by Kyowa Chemical Industry Co., Ltd.) as a thickener,and 2 parts by weight of zinc stearate (SZ-2000, supplied by SakaiChemical Industry Co., Ltd.) was used.

Determination Method of Adhesion Amount of Sizing Agent

A fiber bundle applied with a sizing agent was cut at a length of 1 m,and an ashing treatment was carried out at 450° C. therefor. The weightof the obtained fiber bundle after the ashing treatment was determined,and the adhesion amount of the sizing agent was calculated from theweight reduction rate before and after the ashing treatment. Thedetermination was carried out with respect to 10 fiber bundles, and theaverage value thereof was calculated.

Evaluation Method of Mechanical Property

After placing the fiber-reinforced resin molding material in the centralpart of a flat metal mold (50% in terms of charge rate), it was curedunder a pressure of 10 MPa by a pressurizing type press machine at acondition of about 140° C. for 5 minutes to obtain a flat plate of300×400 mm. Five test pieces (total 10 pieces) each having a size of100×25×1.6 mm were cut out from the obtained flat plate from therespective directions of 0° and 90° when the lengthwise direction of theflat plate was set to 0°, and based on JIS K7074 (1988), the measurementwas carried out. As the mechanical properties, a flexural strength, aflexural modulus, and a CV value (%) of the flexural modulus weredetermined (CV: coefficient of variation).

Example 1

The fiber bundle [A-1] was unwound using a winder at a constant speed of10 m/min, and the unwound fiber bundle was passed through a vibrationwidening roll vibrating in its axial direction at 10 Hz, and after thewidening processing was performed, a widened fiber bundle widened to 60mm was obtained by passing it through a width regulating roll having awidth of 60 mm.

The obtained widened fiber bundle was immersed in a sizing treatmentliquid prepared by diluting the sizing agent [S-1] with a purified waterto apply the sizing agent to the widened fiber bundle, and then, thewidened fiber bundle applied with the sizing agent was subjected to ahot roller at 150° C. and a dryer at 200° C. to dry it and remove themoisture. When the obtained widened fiber bundle having been appliedwith the sizing agent was determined and calculated based on theaforementioned determination method of adhesion amount of sizing agent,it was 3.2%. This is the total adhesion amount including the sizingagent having been applied to an original fiber bundle. Further, thedetermination was carried out while adjusting a tension applied to thefiber bundle so that the fiber bundle width of the widened fiber bundlewas not narrowed by a surface tension.

For the obtained widened fiber bundle having been applied with thesizing agent, a separation means was prepared by setting iron plates forseparation processing each having a projected shape with a thickness of0.2 mm, a width of 3 mm and a height of 20 mm in parallel at equalintervals of 3.5 mm with respect to the width direction of thereinforcing fiber bundle. This separation means was intermittentlypenetrated into and removed from the widened fiber bundle and was woundonto a bobbin to obtain a partially separated fiber bundle.

At this time, the separation means was penetrated into the widened fiberbundle traveling at a constant speed of 10 m/min for 3 seconds to createa separation-processed section, and the separation means was removed for0.2 second, and it was penetrated again, and these operations wererepeated.

The obtained partially separated fiber bundle was separated into 17divided parts in the width direction of the fiber bundle in theseparation-processed section, and at least at one end portion of atleast one separation-processed section, an entanglement accumulationpart accumulated with the entangled parts in which the single fiberswere interlaced was formed. When the partially separated fiber bundlewas manufactured by 1,500 m, the twist of the fibers existing in thefiber bundle passed through in the traveling direction when removing andpenetrating the separation means, without causing yarn breakage andwinding at all, and it was possible to carry out the separationprocessing with a stable width.

Subsequently, the obtained partially separated fiber bundle wascontinuously inserted into a rotary cutter, and the fiber bundle was cutat a fiber length of 25 mm and the cut bundles were sprayed to beuniformly dispersed, whereby a discontinuous fiber nonwoven fabric whosefiber orientation is isotropic was obtained. The areal weight of theobtained discontinuous fiber nonwoven fabric was 1 kg/m′.

The matrix resin [M-1] was uniformly applied to each of twopolypropylene release films using a doctor blade to prepare two resinsheets. The discontinuous fiber nonwoven fabric obtained as describedabove was sandwiched between these two resin sheets from the upper andlower sides, and the resin was impregnated into the nonwoven fabric withrollers to obtain a sheet-like fiber-reinforced resin molding material.At that time, the application amount of the resin was adjusted at thestage of resin sheet preparation so that the weight content ofreinforcing fibers in the fiber-reinforced resin molding material becameto be 47%. With respect to the fiber-reinforced resin molding materialobtained, the fiber-reinforced resin molding material was molded basedon the aforementioned evaluation method of mechanical properties and themechanical properties were evaluated. As a result, the flexural strengthwas 440 MPa, the flexural modulus was 28 GPa, and the CV of the flexuralmodulus was 6%.

Example 2

The evaluation was carried out in the same manner as in Example 1 otherthan a condition where the sizing agent application was performed afterthe fiber bundle [A-1] was unwound using a winder at a constant speed of10 m/min, and the unwound fiber bundle was passed through a vibrationwidening roll vibrating in its axial direction at 10 Hz, and after thewidening processing was performed, a widened fiber bundle widened to 60mm was obtained by passing it through a width regulating roll having awidth of 60 mm, and the separation processing was performed to thewidened fiber bundle to obtain a partially separated fiber bundle. As aresult, the adhesion amount of the sizing agent was 3.3%, the flexuralstrength was 430 MPa, the flexural modulus was 27 GPa, and the CV of theflexural modulus was 8%.

Example 3

The evaluation was carried out in the same manner as in Example 1 otherthan a condition where after the fiber bundle [A-1] was unwound using awinder at a constant speed of 10 m/min and the unwound fiber bundle wasimmersed in a sizing agent treatment liquid, the fiber bundle was passedthrough a vibration widening roll vibrating in its axial direction at 5Hz to obtain a widened fiber bundle finished with sizing agent applying,the separation processing was performed to the widened fiber bundlefinished with sizing agent applying, the prepared partially separatedfiber bundle finished with sizing agent applying was subjected to adrying step to obtain a partially separated fiber bundle. As a result,the adhesion amount of the sizing agent was 3.2, the flexural strengthwas 435 MPa, the flexural modulus was 28 GPa, and the CV of the flexuralmodulus was 7%.

As described above, in any of Examples 1 to 3, it was confirmed thatexcellent mechanical properties (flexural strength, flexural modulus)and low variation were both exhibited. Further, when unwinding thepartially separated fiber bundle and inserting it into the cutter, itcould be unwound stably without causing winding around the bobbin.Furthermore, in the discontinuous fiber nonwoven fabric, the cut fiberbundle kept a convergence as a bundle, and the occurrence of singlefiber fluffs was suppressed.

Further, in Example 1, since the partial separation processing wasperformed after the sizing agent was applied, almost no fluffs wereaccumulated in the separation means, and the separation processing couldbe stably performed. In Example 2, since the sizing agent was appliedafter the partial separation processing was performed, the convergenceof the fiber bundle of the separation-processed section divided by theseparation processing was high, and the occurrence of single fiberfluffs when obtaining the discontinuous fiber nonwoven fabric was mostsuppressed. In Example 3, since the sizing agent was applied and thewidening processing was carried out in the state of so-called wettingthread before drying, the friction between single fibers in the fiberbundle was alleviated and, further, the sizing agent played the role ofa lubricant, it was possible to widen to a target widened width even bya low frequency in vibration.

INDUSTRIAL APPLICABILITY

Our methods can be applied to any fiber bundle in which it is desired toseparate a fiber bundle comprising a plurality of single fibers into twoor more thin bundles, and by applying a sizing agent at an adequatetiming, it can be maintained in an adequate partially separated form. Inparticular, when reinforcing fibers are used, the obtained partiallyseparated fiber bundle can be impregnated with a matrix resin and usedfor any reinforcing fibers composite material.

The invention claimed is:
 1. A method of producing a partially separatedfiber bundle comprising a partial separation processing step thatalternately forms separation-processed sections, each divided into aplurality of bundles, and not-separation-processed sections, wherein,while a fiber bundle to which a sizing agent has been applied andcomprises a plurality of single fibers travels along a lengthwisedirection of the fiber bundle, a separation means provided with aplurality of projected parts is penetrated into the fiber bundle tocreate a separation-processed part, and entangled parts, where thesingle fibers are interlaced, are formed at contact parts with theprojected parts in at least one separation-processed part, thereafterthe separation means is removed from the fiber bundle, and after theseparation means passing through a position of the fiber bundlecorresponding to an entanglement accumulation part including theentangled parts, the separation means is penetrated again into the fiberbundle, wherein an additional sizing agent is applied at an operatorselected time during production of the partially separated fiber bundle.2. The method according to claim 1, wherein the fiber bundle is suppliedto the partial separation processing step after widening the width ofthe fiber bundle.
 3. The method according to claim 2, wherein the fiberbundle is supplied to the partial separation processing step afterapplying the additional sizing agent to the fiber bundle widened inwidth.
 4. The method according to claim 1, further comprising drying theadditional sizing agent at an operator selected time.
 5. The methodaccording to claim 4, wherein a width of the fiber bundle before dryingis widened during the applying the additional sizing agent, the widenedfiber bundle is subjected to the drying, the fiber bundle havingundergone application of the additional sizing agent and the widening issupplied to the partial separation processing step.
 6. A method ofproducing a partially separated fiber bundle comprising a partialseparation processing step that alternately forms separation-processedsections, each divided into a plurality of bundles, andnot-separation-processed sections, wherein a separation means providedwith a plurality of projected parts is penetrated into a fiber bundle towhich a sizing agent has been applied and comprises a plurality ofsingle fibers, while the separation means travels along a lengthwisedirection of the fiber bundle, a separation-processed part is created,and entangled parts, where the single fibers are interlaced, are formedat contact parts with the projected parts in at least oneseparation-processed part, thereafter the separation means is removedfrom the fiber bundle, and after the separation means travels up to aposition passing through a position of the fiber bundle corresponding toan entanglement accumulation part including the entangled parts, theseparation means is penetrated again into the fiber bundle, wherein anadditional sizing agent is applied at an operator selected time duringproduction of the partially separated fiber bundle.